TRACTION CONTROL

[Christian Hack]

> >>
> >>I am wanting to do a DIY traction control.
> >>Does anyone know if OEM systems use ABS/apply brakes or >retard timing
> in

As far as I know standard traction control on most OEM systems does not apply 
brakes in any to reduce wheel slip.

However, the new Euro cars (BMWs and Mercedes in particular) use the ABS system
as a part of their stability control which is essentially a very advanced traction control
system which counters under and oversteer by braking appropriate wheels.

> >the event of lost traction..
> >>If it was retard timing maybe simulating a KNOCK would be a easy >way
> to
> >reduce power and get traction back. The only problem i >would see here
> is
> >how quickly doesn the ECU ( 808/165 ) give me >back full timing once a
> knock
> >has gone away.

The only problem with simulating a knock is whether or not the reduction in power is great
enough to stop the wheel slip and like you say whether it will give back the full timing quick
enough.

I am currently looking into a DIY TC system myself and someone mailed me and suggested a
fly-by-wire system with a variable resistor on the pedal and say a fast enough stepper motor on the 
actual throttle. This would obviously make it real easy to shut the throttle. Would a stepper
motor be fast enough do you think? The newer Euros are using this and I think F1 does too.
Maybe it's not quite as easy as it sounds.

Someone suggest dropping cylinders by stopping the injectors. Could there still be a small
amount of fuel from previous cycles which would result in a very very lean mixture or is that
unlikely to cause a problem?

> >
> >Best idea I've seen is incorporating a front wheel speed sensor,
> >and comparing it to the rears, or driveshaft.
> >Bruce
> >

Comparing front wheel speed to say driveshaft speed in a RWD car would only work
100% if the car had a LSD or even a locked diff. A slippery diff would allow one wheel
to spin on a corner while the other wheel stayed the same speed as the front wheels.

I don't know what speed the drive shaft would be running at in this case. It could be
the slow speed, the fast speed or in between? Somebody else will know this I'm sure.

I do know that early ABS systems were 3 channel though. One channel for each front
wheel and 1 channel for the driveshaft. So it is possible I guess using just the driveshaft.


Christian Hack
christianh at edmi.com.au
EDMI Pty Ltd
Ph : (07) 3888 3066
FAX : (07) 3888 3583